Dresden 2013 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 105: Suche nach Dunkler Materie 1

T 105.5: Vortrag

Montag, 4. März 2013, 12:05–12:20, HSZ-103

Absolute Activity Determination of CaWO₄ Crystals — •Andrea Münster, Andreas Ertl, Achim Gütlein, Jean-Côme Lanfranchi, Walter Potzel, Sabine Roth, Daniel Simon, Stephan Scholl, Moritz von Sivers, Raimund Strauss, Stephan Wawoczny, Michael Willers, Marc Wüstrich, and Andreas Zöller — TU München, Fakultät für Physik, E15, James-Franck-Straße 1, 85748 Garching

The direct Dark Matter search experiment CRESST uses CaWO₄ single crystals as targets for possible WIMP recoils. A particle interaction in the crystal produces phonons as well as scintillation light. As the light signal is dependent on the kind of interacting particle, a particle discrimination on an event-by-event basis is feasible. The observed background is mainly due to intrinsic radioactive impurities of the CaWO₄ target. An activity of this intrinsic contamination can be determined with the investigation of α-decays in the crystal.

Up to now, CaWO₄ crystals were produced by suppliers in Russia and Ukraine. Since 2011 we are able to grow CaWO₄ crystals in a Czochralski furnace installed in the crystal laboratory of TU Munich, which has the advantage to better meet the requirements of CRESST and to ensure the availability of CaWO₄ crystals for the successive future multi-material experiment EURECA. To check the radiopurity, first self-grown crystals were investigated in test measurements.

In this talk we will present the results for absolute α-activities of self-grown crystals and compare them to α-activities of the crystals installed in the last CRESST run (Run32).